数据:能够输入计算机并能被计算机程序识别和处理的信息集合
数据库:数据库是在数据库管理系统和控制之,存放存储介质上的数据集合。
基于嵌入式linux的数据库主要有Sqlite,firebird,berkeley db
firebird是关系型数据库,功能强大,支持存储过程,SQL兼容等
SqLite关系型数据库体积小支持ACID事务
Berkeley DB中并没有数据库服务器的概念它的程序直接链接到应用程序中
extreme DB是内存数据库运行效率高
SQlite的源码是C语言,其源码完全开发SQlited第一个Alpha版本诞生于2000年5月,他是一个轻量级的嵌入式数据库
SQlite的特性:
零配置,无需安装的管理配置
存储在单一磁盘文件中的一个完整程序
数据库文件可以在不同字节顺序的机器中自由共享
支持数据库大小2TB
比目前留下的大多数数据库对数据的操作更快
1、在线安装
sudo apt-get install sqlite3
2、相关库依赖
sudo apt-get install libsqlite3-dev
安装完成后数据sqlite3即可进入数据库模式
1、系统命令
以.开头的命令:.help(帮助) .quit(退出) .schema(查看表结构)
2、sql命令
基本的sql命令,不以.开头但是要以;结尾
创建一张数据库的表stu
create table stu(id Integer,name char,score Integer);
插入一张记录
insert into stu values(1001,'Nike',99);
插入部分字段记录
Insert into stu(name,score) values('Jan',100);
查询所有记录
select *from stu;
查询数据库部分内容字段
select name,score from stu;
根据属性查询
select *from stu where score = xxx;
select *from stu where score = xxx and name = 'xxx';
删除一条记录
delete from stu where score = xxx;
delete from stu where name = 'xxx';
更新一条记录
update stu set name = 'xxx' where id = xxxx;
update stu set name = 'xxx',score = xxx where id = xxx;
添加一列
alter table stu add column address char;
删除一列(三步)
1.创建一张表提取字段
create table stu1 as select id ,name,score from stu;
2.删除原有表
drop table stu;
3.将新的表的名字该成原有的表名字
alter table stu1 rename stu;
#include
#include
#include
#define DATABASE "student.db"
int do_insert(sqlite3 * db)
{
int id = 0;
char name[32] = {0};
int score = 0;
char sql[128] = {0};
char *errmsg;
printf("please input id:");
scanf("%d",&id);
printf("please input name:");
scanf("%s",name);
printf("please input score:");
scanf("%d",&score);
sprintf(sql,"insert into stu values(%d,'%s',%d);",id,name,score);
if(sqlite3_exec(db,sql,NULL,NULL,&errmsg) != SQLITE_OK)
{
printf("%s\n",errmsg);
exit(-1);
}
else
{
printf("insert success\n");
}
return 0;
}
int do_delete(sqlite3 *db)
{
int id = 0;
char sql[128] = {0};
char *errmsg;
printf("please input delete id:");
scanf("%d",&id);
sprintf(sql,"delete from stu where id = %d ",id);
if(sqlite3_exec(db,sql,NULL,NULL,&errmsg) != SQLITE_OK)
{
printf("%s\n",errmsg);
exit(0);
}
else
{
printf("delete success\n");
}
return 0;
}
int callback(void *param,int f_num,char **f_value,char **f_name)
{
int i = 0;
for(i = 0;i < f_num;i++)
{
printf("%s",f_value[i]);
}
printf("\n");
return 0;
}
int do_query(sqlite3 *db)
{
char sql[128] ={0};
char *errmsg;
sprintf(sql,"select *from stu");
if(sqlite3_exec(db,sql,callback,NULL,&errmsg) != SQLITE_OK)
{
printf("%s\n",errmsg);
exit(-1);
}
else
{
printf("query success\n");
}
return 0;
}
int do_query2(sqlite3 *db)
{
char sql[128] = {0};
char *errmsg;
char **resultp;
int nrow;
int ncloumn;
int i = 0,j = 0,index = 0;
sprintf(sql,"select *from stu");
if(sqlite3_get_table(db,sql,&resultp,&nrow,&ncloumn,&errmsg) != SQLITE_OK)
{
printf("%s\n",errmsg);
exit(-1);
}
else
{
printf("query success\n");
}
index = ncloumn;
for(j =0;j<ncloumn;j++)
{
printf("%-11s",resultp[j]);
}
printf("\n");
for(i = 0;i<nrow;i++)
{
for(j =0;j<ncloumn;j++)
{
printf("%-11s",resultp[index++]);
}
}
}
int do_update(sqlite3 *db)
{
int id = 0;
char sql[128] = {0};
int score = 0;
char *errmsg;
printf("please input id:");
scanf("%d",&id);
printf("please input score:");
scanf("%d",&score);
sprintf(sql,"update stu set score = %d where id = %d",score,id);
if(sqlite3_exec(db,sql,NULL,NULL,&errmsg) != SQLITE_OK)
{
printf("%s\n",errmsg);
exit(-1);
}
else
{
printf("update success\n");
}
return 0;
}
int main(void)
{
sqlite3 *db;
char *errmsg;
int cmd = 0;
if(sqlite3_open(DATABASE,&db) != SQLITE_OK)
{
printf("%s\n",sqlite3_errmsg(db));
exit(-1);
}
else
{
printf("open sqlite success\n");
}
if(sqlite3_exec(db,"create table stu(id Integer,name char,score Integer);",NULL,NULL,&errmsg) != SQLITE_OK)
{
printf("%s\n",sqlite3_errmsg(db));
exit(1);
}
else
{
printf("create or open table success\n");
}
while(1)
{
printf("-----------------------------------------------\n");
printf("1:insert,2:delete,3:quert,4:update,5:quit\n");
printf("----------------------------------------------\n");
printf("please input cmd:");
scanf("%d",&cmd);
switch(cmd)
{
case 1:do_insert(db);break;
case 2:do_delete(db);break;
case 3:do_query(db);break;
case 4:do_update(db);break;
case 5:sqlite3_close(db);exit(-1);break;
default:break;
}
}
return 0;
}
测试结果